Abstract: Porous polyolefin membrane with a porosity of at least 20%, which is steam sterilizable at elevated temperature, wherein the polyolefin is polyethylene with an intrinsic viscosity of at least 5 dl/g and the membrane shows a shrinkage of at most 4% in every direction in the plane of the membrane when exposed to steam with a temperature of 134.degree. C. for 10 minutes.

Abstract: Process for producing a steam-sterilizable porous polyolefin membrane with a porosity of at least 20% and a shrinkage of 4% at most in every direction in the plane of the membrane in steam sterilization by subjecting a porous stretched film to a shrink treatment at a temperature equalling at least the sterilization temperature, but below the melting point of the polyolefin, in which treatment the permitted shrinkage is at least 95% of the critical shrink factor of the film in every direction in the plane of the film and a membrane of polyethylene with an intrinsic viscosity of at least 5 dl/g, steam-sterilizable at 134.degree. C.

Abstract: A composite membrane including a microporous polymer film having a high air permeability as a support and a non-porous gas or vapor separating coating having a thickness of not more than 15 .mu.m is provided. The separation factor and flux of the membrane are substantially equal to those of the coating. Also provided is a process for the manufacture of a composite membrane including a support and a gas or vapor separating coating by drawing a polymeric film to which the coating material has been applied, and increasing the viscosity of the coating during drawing.

Abstract: Process for the production of a film having improved bursting strength by applying a recessed line pattern to a porous film produced from a solution of polyethene and from which the solvent has been removed, at a temperature below the melting point of the polyethene, and subsequently stretching the film biaxially with a degree of stretching of at least 2 x in each of the two directions, the surface area of the film increasing by at least a factor 8, and a porous film having high bursting strength.

Abstract: Microporous film of ultra high molecular weight polyethylene with a high degree of moisture vapor transmission rate and a permeability to air that lies within a narrow range and a process for the production of a film with a high degree of moisture vapor transmission rate and a permeability to air that lies within a narrow range from a polyolefin by extruding a solution of the polyolefine in a first solvent, followed by cooling, the removal of the solvent and stretching of the film, in which the surface of one and only one side of the film is brought into close contact with a second solvent for the polyolefin before the film is contacted with the cooling agent.

Abstract: Microporous film of polyethylene with a high degree of moisture vapour transmission rate and permeability to air and a process for the production of such a film from a polyolefine by extruding a solution of the polyolefine in a first solvent, followed by cooling, the removal of the solvent and stretching of the film, in which both sides of the film are brought into close contact with a second solvent for the polyolefine before the film is contacted with the cooling agent.

Abstract: Microporous film of polyethylene with a high degree of moisture vapor transmission rate and permeability to air and a process for the production of such a film from a polyolefine by extruding a solution of the polyolefine in a first solvent, followed by cooling, the removal of the solvent and stretching of the film, in which both sides of the film are brought into close contact with a second solvent for the polyolefine before the film is contacted with the cooling agent.

Abstract: Microporous film of ultra high molecular weight polyethylene with a high degree of moisture vapor transmission rate and a permeability to air that lies within a narrow range and a process for the production of a film with a high degree of moisture vapor transmission rate and a permeability to air that lies within a narrow range from a polyolefine by extruding a solution of the polyolefine in a first solvent, followed by cooling, the removal of the solvent and stretching of the film, in which the surface of one and only one side of the film is brought into close contact with a second solvent for the polyolefine before the film is contacted with the cooling agent.